1. Technical Field
The present invention relates to a backlight unit including a plurality of light sources, and an electro-optical device and an electronic apparatus using the backlight unit.
2. Related Art
In the related art, a liquid crystal display device (LCD) as an electro-optical device includes a display panel displaying an image and a backlight unit disposed on the rear surface of the display panel and emitting light toward the display panel.
As the backlight unit, a direct-type backlight unit having a plurality of light sources arranged directly below the display panel has been known (for example, see JP-A-2007-80798).
The direct-type backlight unit disclosed in JP-A-2007-80798 includes a box-like case having a bottom plate, a plurality of light sources arranged inside the case, and a display panel disposed so as to cover an opening of the case. The case has the bottom plate and a plurality of side walls obliquely erected from the edges of the bottom plate. The plurality of light sources are arranged on the bottom plate in a zigzag shape. In addition, the plurality of side walls are erected at the same inclination angle.
Light emitted from the plurality of light sources and light reflected from inner surfaces (reflection surfaces) of the plurality of side walls irradiate to an irradiation area surrounded by the upper ends of the plurality of side walls.
In the backlight unit disclosed in JP-A-2007-80798, however, since the plurality of light sources are arranged in a zigzag shape, the light sources distant from the side walls and the light sources close to the side walls exist. Therefore, in the light sources distant from the side walls, an amount of light reflected from the reflection surfaces of the side walls is reduced. In contrast, in the light sources close to the side walls, an amount of light reflected from the reflection surfaces of the side walls is increased. For this reason, a problem may occur in that an amount of light in the irradiation area becomes non-uniform. Moreover, the amount of light reflected from the reflection surfaces of the side walls is reduced in the light sources distant from the side walls. Therefore, a problem may occur in that an amount of light emitted to a side of the outside frame of the irradiation area is reduced, thereby deteriorating optical characteristics.
On the other hand, in a liquid crystal display device which is an assembly of the backlight unit and the display panel, when the amount of light in the irradiation area of the backlight unit is not uniform, a problem may occur in that display irregularities such as brightness irregularity and color irregularity occurs in an effective display area where an image of the display panel is displayed.